Belt tensioner and method of making the same

Abstract

A tensioner for a power transmission belt that is adapted to be operated in an endless path and a method of making the same are provided, the tensioner comprising a support unit for being fixed relative to the belt, a belt engaging unit carried by the support unit and being movable relative thereto, a mechanical spring unit operatively associated with the support unit and the belt engaging unit for urging the belt engaging unit relative to the support unit and against the belt with a force to tension the belt, and a fluid dampening unit operatively associated with the support unit and the belt engaging unit to dampen the movement of the belt engaging unit relative to the support unit in at least one direction of movement thereof, the fluid dampening unit comprising a rotary dampening unit. The rotary dampening unit and the spring unit are coaxially aligned. The support unit has an opening passing therethrough for receiving a fastening member that will fasten the support unit to a vehicle bracket or the like. The opening is disposed coaxially through the rotary dampening unit and the spring unit.

What is claimed is: 
     
       1. In a tensioner for a power transmission belt that is adapted to be operated in an endless path, said tensioner comprising a support means for being fixed relative to said belt, a belt engaging means carried by said support means and being movable relative thereto, mechanical spring means operatively associated with said support means and said belt engaging means for urging said belt engaging means relative to said support means and against said belt with a force to tension said belt, and dampening means operatively associated with said support means and said belt engaging means to dampen the movement of said belt engaging means relative to said support means, said dampening means having a movable means and a longitudinal axis on which said movable means moves, said spring means having a longitudinal axis and being spiraled about said axis thereof, said support means comprising a shaft means having a longitudinal axis and being fixed from movement relative to said belt engaging means, the improvement wherein said shaft means carries said dampening means and said spring means in spaced apart side-by-side relation thereon with said axis of said shaft means being substantially coaxial with said axes of said dampening means and said spring means whereby said dampening means and said spring means are coaxially spaced apart and are coaxially aligned by said shaft means, said belt engaging means having a portion thereof disposed between said dampening means and said spring means and being rotatably carried by said shaft means so as to rotate relative to said shaft means whereby said dampening means and said spring means are coaxially spaced apart from each other by said portion of said belt engaging means, said shaft means having an opening means passing therethrough for receiving a fastening member that will fasten said support means to a bracket or the like, said opening means being disposed coaxially through said dampening means and said spring means, said shaft means comprising a tubular member disposed coaxially through said dampening means and said spring means, said tubular member having opposed open ends whereby said tubular member defines said opening means that passes completely therethrough, a sleeve means rotatably disposed on said tubular member, said belt engaging means comprising an arm having opposed ends, one of said opposed ends of said arm being interconnected to said sleeve means to rotate in unison therewith, said belt engaging means further comprising a pulley for engaging said belt, said pulley being rotatably carried by the other of said opposed ends of said arm, said spring means comprising a coiled torsion spring having an inner end and an outer end, said inner end of said spring being operatively interconnected to said sleeve means and said outer end of said spring being operatively interconnected to said tubular member, and a cup-shaped housing having a closed end and an open end, said closed end of said housing being secured to one of said ends of said tubular member and said open end of said housing being disposed closely adjacent said one end of said arm to be effectively closed thereby, said spring being disposed in said housing, said outer end of said spring being operatively interconnected to said housing. 
     
     
       2. A tensioner as set forth in claim 1 wherein said dampening means comprises a rotary dampening means having an outer ring member and an inner ring member disposed in said outer ring member, said members being arranged for relative rotational movement therebetween, said outer ring member being operatively interconnected to said support means, said inner ring member being operatively interconnected to said belt engaging means and being said movable means of said dampening means. 
     
     
       3. A tensioner as set forth in claim 2 wherein said inner ring member has a plurality of circumferentially spaced apart radially outwardly disposed vane means, said outer ring member having a plurality of circumferentially spaced apart radially inwardly disposed vane means cooperating with said vane means of said inner ring member to restrict relative rotational movement between said members in at least one direction. 
     
     
       4. A tensioner as set forth in claim 1 wherein said outer ring member is interconnected to the other end of said tubular member. 
     
     
       5. A tensioner as set forth in claim 1 wherein said inner ring member is rotatably disposed on said tubular member. 
     
     
       6. A tensioner as set forth in claim 5 wherein said inner ring member is operatively interconnected to said sleeve means to rotate in unison therewith relative to said tubular member.